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/*
Copyright (C) 2021 Fredrik Johansson
This file is part of FLINT.
FLINT is free software: you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License (LGPL) as published
by the Free Software Foundation; either version 3 of the License, or
(at your option) any later version. See <https://www.gnu.org/licenses/>.
*/
#include "ca.h"
static void
_ca_set_fmpq(ca_t x, const fmpz_t p, const fmpz_t q, ca_ctx_t ctx)
{
_ca_make_fmpq(x, ctx);
fmpz_set(CA_FMPQ_NUMREF(x), p);
fmpz_set(CA_FMPQ_DENREF(x), q);
}
void
ca_fmpq_poly_evaluate(ca_t res, const fmpq_poly_t poly, const ca_t x, ca_ctx_t ctx)
{
if (fmpq_poly_is_zero(poly))
{
ca_zero(res, ctx);
}
else if (fmpq_poly_length(poly) == 1)
{
_ca_set_fmpq(res, poly->coeffs + 0, poly->den, ctx);
}
else if (CA_IS_QQ(x, ctx))
{
fmpq_t t;
fmpq_init(t);
fmpq_poly_evaluate_fmpq(t, poly, CA_FMPQ(x));
ca_set_fmpq(res, t, ctx);
fmpq_clear(t);
}
/* todo: fast modular composition for number field elements */
/* else if (CA_FIELD_IS_NF(CA_FIELD(x, ctx))) */
else
{
ca_t t; /* for aliasing */
slong i, n;
ca_init(t, ctx);
/* todo: rectangular splitting? */
n = fmpq_poly_degree(poly);
ca_set_fmpz(t, poly->coeffs + n, ctx);
for (i = n - 1; i >= 0; i--)
{
ca_mul(t, t, x, ctx);
ca_add_fmpz(t, t, poly->coeffs + i, ctx);
}
ca_div_fmpz(res, t, poly->den, ctx);
ca_clear(t, ctx);
}
}